A computer screen during a simulated oil spill training exercise in Indian River, about 30 miles south of Mackinaw City, in Sept. 2014. More than 200 members from local, state and federal agencies participated in a drill with Enbridge Energy to simulate what would happen if there was a major oil spill of Line 5. (MLive file photo | Fritz...

This U.S. Environmental Protection Agency photos shows technicians in personal protective equipment measuring pipe before cutting and removing the section from the Enbridge pipeline oil spill into the Kalamazoo River in 2010.

A September 2011 file photos shows an excavator diging into the bottom of Morrow Lake in Comstock Township during cleanup of the 2010 Enbridge oil spill into the Kalamazoo River. The company also operates Line 5 under the Straits of Mackinac. (Kalamazoo Gazette file photo | Jonathon Gruenke)

An August 26, 2011 aerial view of excavators digging into islands in the Kalamazoo River during cleanup of the Enbridge Inc. oil spill from Line 6B in 2010. The company also operates Line 5 under the Straits of Mackinac. (Kalamazoo Gazette file photo | Jonathon Gruenke)

Underwater cameras help Enbridge workers survey the pipeline lying at the bottom of the Straits of Mackinac. Maintenance work was done on the pipeline in the fall of 2014. (MLive file photo | Fritz Klug)

The Minnesota DNR applied the biopesticide Zequanox to a treatment area in Christmas Lake in Hennepin County in October 2014. The environmentally friendly pesticide was one of several treatments to kill zebra mussels in the lake. (Courtesy | Minnesota DNR).

The Minnesota DNR applied the biopesticide Zequanox to a treatment area in Christmas Lake in Hennepin County in October 2014. The environmentally friendly pesticide was one of several treatments to kill zebra mussels in the lake. (Courtesy | Minnesota DNR).

The Minnesota DNR applied the biopesticide Zequanox to a treatment area in Christmas Lake in Hennepin County in October 2014. The environmentally friendly pesticide was one of several treatments to kill zebra mussels in the lake. (Courtesy | Minnesota DNR).

The Minnesota DNR applied the biopesticide Zequanox to a treatment area in Christmas Lake in Hennepin County in October 2014. The environmentally friendly pesticide was one of several treatments to kill zebra mussels in the lake. (Courtesy | Minnesota DNR).

The Minnesota DNR applied the biopesticide Zequanox to a treatment area in Christmas Lake in Hennepin County in October 2014. The environmentally friendly pesticide was one of several treatments to kill zebra mussels in the lake. (Courtesy | Minnesota DNR).